Now sure if mine is pregnancy related, i will know tomorrow with the us, BUT i first noticed at the 20 week mark, very faint and went from under my chest in the center straight down over my belly b___ton to my pelvis, it keeps getting a little darker every day

Mine starts at my pelvis and ends about an inch before my belly b___ton. Whether you get it or not depends on your complexion as it's a pigmentation thing. I am olive skinned whereas my friend (who is the same gestation as me) is very very fair and doesn't have a line at all.